Diamond cutting machine



Dec. 25, 1951 c, HANS 2,579,666

DIAMOND CUTTING MACHINE Filed March 20, 1948 2 SHEETS- SHEET l"HHEHHHHHI ea H.

'jia /eizlar 620%5A. Ham/5 g g/W MW Dec. 25, 1951 c. AHANS DIAMONDCUTTING MACHINE 2 SHEETS-SHEET 2 Filed March 20, 1948 jivzxemior ,6 4M,A55 is J T g: Z0

Patented Dec. 25, 1951 DIAMOND CUTTING MACHINE Charles A. Hans,Wood-Ridge, N. J., assignor to Jewel-Smiths, Inc., Boston, Mass., a.corporation of Massachusetts Application March 20, 1948, Serial No.16,015

This invention relates to machines for grinding facets on precious andsemi-precious stones and, more especially, to improvements in a machinefor grinding facets peripherally of the girdle between the crown andpavilion of a diamond, as shown in Edward Goldstein Paten Number2,340,659, of February 3, 1944.

It is customary to cut precious and semiprecious stones, sometimescalled brilliants, so that they have a cone-shaped crown and aconeshaped pavilion located base to base with a narrow band or girdlearea between them. The crown is truncated and has a surmounting flatsurface called the table and its conical surface is faceted. Thepavilion has a truncated apex and its conical surface is also faceted.Prior to the aforesaid Patent No. 2,340,659 the girdle was leftunpolished, that is, rough and uncut. In that patent, however, there isdisclosed a novel diamond in which the girdle is cut by grinding to forma plurality of polished facets. The provision of these polished facetsin the area of the girdle improves the brilliance of the diamond,provides for better anchoring surfaces when the diamond is placed in asetting, and permits easier cleaning as well as other advantages whichwill appear by reference to that patent. The conventional machine forgrinding stones has a dop for holding the stone in a position to beoperated upon by a lap, but such machines have been designed primarilyto cut the facets on the crown and pavilion as distinguished from thegirdle, and are not suitable for cutting facets in the girdle area. Inmost of such prior machines the stone has been cemented to the dop withan adhesive or sealing wax with the consequent requirement that when thesucceeding cut was to be made the stone had to be removed, turnedthrough the proper angle and re-fastened to the dop before this nextoperation could be performed. While this was not particularlydisadvantageous when cutting the comparatively large facet areas of thepavilion and crown which require a long time so that the time requiredto remove and replace the stone was not disproportionately large,considerable delay and added cost are caused by having to detach andreattach the stone for each out along the girdle areas as these cuts canbe made fairly rapidly. Some prior machines have employed a dop providedwith mechanical means for holding the stone by engagement with thepavilion and/or the crown, but, on the whole, these have not provedentirely satisfactory because they have been too exacting to manipulatebecause the 2 Claims. (C1. 51-229) parts have not held the stonesecurely in place and because the parts obscured or concealed the stoneso that the lapidary was unable clearly to see the stone during thegrinding operation.

Objects of this invention are to improve the prior machines in suchaspects as to make them especially suitable for cutting the minutefacets at the girdle area of a stone, regardless of its size, tominimize damage to the faceted surfaces, to provide for smoother andeasier operation, better visibility of the work during the grindingoperation, and greater efiiciency without sacrificing any of thefeatures and advantages of prior machines.

According to the invention, the machine comprises essentially a drivenlap having a substantially horizontal grinding face composed of asuitable abrasive material, a dop into which the stone may be set andsecured, and means for effecting movement of the dop to and from thegrinding surface so as to bring the portion of the stone being groundinto juxtaposition with the grinding surface and to turn it about avertical axis normal to the grinding surface in order to orient thestone, that is, to bring the grain thereof substantially parallel to thedirection of movement of the grinding surface at its point of contacttherewith. As illustrated, the dop is rotatably suspended by a spindleapproximately midway between the center of rotation of the lap and itsperipheral edge near one end of a horizontal arm, the opposite end ofwhich is fixed to a screw by means of which it and hence the dop may bemoved vertically. The spindle is free to move vertically a limitedamount in the arm, and a knob fixed to the upper end of the spindleaffords means for rotating it about its vertical axis. A look screw isarranged in a boss integral with the arm and may be set up to lock thespindle in any given angular position Without interfering with itsvertical movement in the arm. The dop itself includes a block fixed tothe lower end of the spindle, the block having a slot therein from itslower end upwardly to form spaced, parallel walls joined at their top bya transverse wall, and between the walls there is situated the diamondclamping members. One element of the clamping members is rigidlyfastened between the walls, and to this member there are fastened aplurality of guide pins upon which is arranged to slide the othermember. These members are in the form of legs, and near the lower end ofeach leg there is journaled in a bearing sleeve, set into an aperture inthe leg, a spindle. On the inner end of each spindle there is aspecially shaped surface for engagement with the stone, and a screw isrotatably fixed in one leg and threaded into the other so that uponrotation of the screw the legs may be drawn toward each other to clampthe stone between the specially shaped surfaces. In a preferred form ofthe invention one of the clamping members is recessed and has a facetedinner surface for engagement with the pavilion, and the other has a fiatsurface for engagement with the table of the stone. members is rotatableabout axes parallel to the axis of the stone, one of which is coincidentwith the vertical axis of the stone, and the other of which is offsettherefrom. In this form the axes may be parallel to the surface of thelap. but preferably are inclined at an angle thereto, this angle beingselected in accordance with the angle at which the facets are to be cut.To this end the legs are inclined to the spindle upon which the block issupported at an angle which is a complement of the angle at which thefacets are to be ground. In this form, that is wherein the legs areinclined, the lower ends of the legs are eccentric with respect 'to theaxis of the spindle which supports the dop so that rotation of the dopwill move the diamond bodily in a circle over the surface of the lap'rather than about a point. The legs are tapered near their lower endsand recessed on their inner surfaces, and the clamping members haveannular shoulders for contact therewith. Rotation of the screw tom-drawthe legs together therefore frictionally engages the clamping memberswith the diamond and their shoulders with the legs to immobilizeclamping members as a whole. To permit rotation of the diamond about itsvertical. axis, the screw is released slightly and the dia-- mcnd maythen be rotated by turning a knob attached to one of .the spindleswithout releasing the diamond.

The invention will now be described with reference to the accompanyingdrawings in which:

Fig. 1 is a side elevation of apparatus with which the present inventionis concerned, showing a driven lap, a dop for holding a precious orsemi-precious stone, and means for adjustably supporting the dop inoperating relation to the lap;

Figs. 2 and 3 show a vertical elevation and top plan view of a stone inwhich the facets in the girdle portion are cut at an angle to thevertical axis of the stone;

Figs. e and 5 show corresponding views of a stone in which the facets inthe girdle area are cut parallel to the vertical axis of the stone;

Fig. 6 is a diagrammatic section through the.

vertical axis of the stone showing only one-half thereof andillustrating the angle which the girdle facets made with the verticalaxis of the stone;

Fig. '7 shows a corresponding section in which the plane of the facetsin the girdle is parallel to the axis of the stone;

Fig. 8 is a vertical side elevation of the dop partly insection;

Fig. 9 is a vertical end view of the dop shown in Fig. 8 looking fromthe right-hand side thereof;

a Fig. 10 is a side elevation of the dop enlarged with a stone clampedtherein and resting in engagement with the upper grinding surface of thelap;

Fig. 11 is a slightly modified form of apparatus 'wherein the dop isconstructed to hold the stone Each of the clamping with its verticalaxis parallel to the grinding surface of the lap; and

Fig. 12 is an end elevation of the clamping member which receives thepavilion showing its inner surface faceted.

Referring to the drawings, there is shown in Fig. 1 an apparatus it forcutting, by grinding, facets around the girdlearea of a brilliant, forexample, a diamond. The conventional diamond is cut, as illustrated inFigs. 2 to 7 inclusive, to have a crown portion C surmounted by a flattable portion T and a subjacent pavilion portion P which terminates in atruncated apex called the culet c. The crown and pavilion are ground toprovide a large number of facets F, F, and, according to at least onemethod of cutting, 32 facets are cut in the crown and 24 in thepavilion.

.To avoid too sharp and hence too fragile corners where the planesurfaces of the facets on the crown meet those on the pavilion what isknown in the trade as the girdle portion G is left unground between thecrown and pavilion portions. The unground girdle is rough,non-reflective and a place for catching and retaining dirt, thusreducing the brilliance of the stone and making it difficult to keep itclean. In accordance with the aforesaid patent, however, this girdlearea is ground to provide a plurality of facets f to afford among otheradvantages increased brilliance of the stone, a better anchoring areafor the setting, and to facilitate keeping it clean. In one form,,asshown in that patent, the planes or fiat faces of the facets,illustrated by the line a/a of Fig. 6, are inclined at a small anglewhich may vary as desired from approximately 10 to 30] from the verticalaxis ra: of the stone toward the crown so that, as shown in Fig. 3, thesurfaces of the facets are seen when looking down upon the top of thebrilliant. This increases the sparkle and brilliance of the-diamond.However, in another form of the invention illustrated by the line 17-?)of Fig. 7, the planes of the facets are made parallel to its verticalaxis :c-.r.

Heretofore there have been numerous grinding, polishing and lappingmachines, for cutting the facets on the crown and pavilion portions ofstones, and it has been customary to mount the work which is to beground in a carrier commonly known as a dop and to hold the work bymeans 7 ting the facets on the crown and pavilion, and

in most instances the stone has been fastened to the dop by means ofcement, sealing wax or some other adhesive compound. Since the operationof forming, by cutting, the facets on the crown or pavilion is a slowone, it made little difference that it was necessary to remove the workafter In the grinding of the facets around the girdle area, however, thearea involved during. any given operation is so small that a given facetmay be ground in a very short time, and hence the time required todismount and re-mount the work between the grinding of each successivefacet becomes a disproportionately large part of the entire operation,with the result that time is lost and the cost is increased. Theinvention is primarily concerned, with the provision of an improved dopfor holding a stone in a position to grind the facets in the girdle areaat the required angle and which will permit indexing of the work forgrinding the successive facets circumferentially of the girdle withoutdismounting and re-mounting the work for each successive grindingoperation. Further objects are to reduce chattering, eliminatescratching, and to provide means for holding any size stone.

The apparatus as shown, Fig. 1, comprises es sentially a grinding lap I2which is motor driven, a dop M for supporting the work in operativeposition with respect to the lap, an adjustable overhanging arm l6 fromwhich the dop is susl pended, and a supporting structure or frame It forthe arm.

The frame or supporting structure It is com prised of an upright hollowpost 22, stiffened by a web 23, fixed at its lower end to a horizonalbase which extends laterally from one side thereof. A bracket 24 isfastened to the post 22 substantially midway betweenits upper and lowerends in a position to project horizontally over the base, and isconstructed to hold a motor M with its shaft 26 in a substantiallyvertical position. To the upper end of the shaft 23 there is fixed ahorizontal circular table 28 which is adapted to be rotated by themotor, and fastened to the upper surface of the table is a flat grindingdisk 3!], made of an abrasive material, suitable for cutting diamonds,the table 28 and disk 30 constituting what is known in the trade as alap or skeif. The dop I4 is supported above the lap and at a distancefrom the center of rotation thereof, that is, substantially midway ofits axis of rotation and its periphery by a spindle 32, to the lower endof which it is fastened, which is mounted near the free end of the armI6 for rotation about its vertical axis and for vertical movementtherein. As illustrated, the spindle 32 passes through and is splined ina sleeve 34 set into a vertical aperture 36 formed in the arm [6 andfree to rotate therein. A collar 40, fixed to the upper end of thespindle, engages the top of the arm and prevents the spindle and sleevefrom slipping downwardly through the aperture 35. A knob 42is also fixedto the spindle and serves to facilitate rotation thereof about itsvertical axis with respect to. the lap to change the position of thedop, for example, to permit orienting the stone so. that it may beground in the direction of its grain structure. In order that the dopmay be fixed at any given angular position about its vertical axis, butwithout inhibiting free vertical movement, a lock screw 31 is threadedinto an aperture 39 formed in a boss 4! on the underside of the armagainst the sleeve, and a knob 43 is provided for setting it up orbacking it off. The arm I6 is in turn fastened to the upper end of along screw 44 which projects downwardly therefrom into the hollow post22. The threaded portion of the screw passes through a threaded aperturein a worm gear 46 set into a recess in the hollow post 22 so that itwill not have vertical movement but may be rotated, with which theremeshes a worm 48 mounted on a horizontal shaft 49, journaled in the web23. The shaft projects laterally from the post and may be provided witha handle, not shown, for effecting rotation thereof. By rota tion of thehandle, the screw 44 may be raised or lowered in the pest, and by way ofthe arm Hi the dop l4 may be raised and lowered a corresponding amountto bring the dop close to the tween the walls 52 by means of pins 58.

surface of the lap. With this construction it is the weight of the dopwhich holds the stone against the top of the skeif during the grindingoperation.

The dop, as shown in Figs. 8, 9 and 10, comprises essentially asupporting block 59 fastened to the lower end of the spindle 32, withwhich there are associated movable members designed to engage and holdthe work in a securely clamped position during the grinding operationbut capable of manipulation to index, that is, to turn the work fromposition to position to permit grinding successive facets thereon or torelease the work. The form of the dop illustrated in the aforesaidfigures is designed to cut the facets circumscribing the girdle at anangle to the vertical axis, that is, inclined toward the crown, and tothis end a slot is formed in the block from its bottom side upwardly soas to provide a pair of spaced, depending walls 52 separated by asloping surface 54 (Fig. 8) inclined to the axis of the spindle 32 at anangle which is the complement of the angle at which the facets are to becut. A leg 55 is rigidly fastened within the slot be- The leg 56 isinclined with respect to the axis of the spindle 32, that is, it issubstantially normal to the surface 54 so that its lower end 60 iseccentric with respect to the axis of the spindle and is tapered asshown in Fig. 9. In the lower tapered end of the leg 56 there isatransverse aperture 62 which is parallel to the surface 54 in whichthere is disposed a bearing sleeve 64. Within the bearing sleeve thereis rotatably positioned a shaft 56 upon the inner end of which there isfastened a circular disk 68 having a fiat, smooth inner face I0 and afiat, annular shoulder H which bears against the leg bordering theaperture 62. The inner surface of the leg is recessed at 13 so as toaccommodate the disk 68 with its,

end face 10 substantiall below the plane of the im'ier surface of theleg and to provide a bearing surface for the annular shoulder H. Theterminal end of the leg 56 is cut off at an angle so as to besubstantially parallel to the surface of the lap, and the dimensions ofthe table are such that its periphery does not project beyond the end ofthis leg. Since the spindle is not fast the disk may be dismounted atany time and replaced by a different size disk.

There are fixed in the upper portion of the leg 56 a plurality of spacedparallel pins 12 (Figs. 8, 10 and 11), these pins being so located thatone of them is situated on the center line of the leg near the upper endthereof, while the other is situatedon the center line of the leg nearthe lower (Fig. 9). The pins 12 are fixed in the leg so that theyproject from the inner surface thereof substantially parallel to thesurface 54, and there is slidably mounted on their free ends a leg 74corresponding to the leg 56. To this end the leg 14 is provided with aplurality of apertures 16 for receiving the ends of the aforesaid pins12. The lower end of the a transverse aperture I8 in which there is posileg 14 is tapered as is the leg 56, and has in it tioned a sleeve forthe accommodation of a shaft 82 for rotation therein, the shaft havingat its inner end a head 84 and at its outer end a knob 86. The head 84,as shown in Figs. 8 and 10, has at its under side an annular shoulder 88for engagement with the inner surface of the leg 14, the latter beingrecessed at 89 in a manner corresponding to the recess 13 in the leg 55.The inner end face of the head 84 is recessed 7 at '90 (Fig. 13) and iscut to have a plurality internal facets. 92 which correspond in numberanddimensions to the facets in the pavilion portion of the work which isbeing operated upon. As'thus constructed, the work, that is a stone, ismounted between the disk 88 and thehead 84, with the table T of thestone in engagement With the inner, flat surface is of the disk 33,

and with the pavilion P seated in the recess 99, as shown in Fig. 10. Itis to be observed that the bearing apertures 62 and 863 in the legs 56and M are not in axial alignment so that-the axes of rotation of thedisk and head .do. not coincide. This axis of the head is coincidentwith the vertical axis of the stone, and is inclined to the surface ofthe lap at the angle at which the facet is to be cut. The axis of thedesk, however, while being correspondingly inclined to the lap, isoffset and parallel to the axis of the head so that it lies outside ofthe vertical axis of the stone, hence the surface of the disk iseccentric with respect to the table of the work. It is also to beobserved that since the lower end of the arm 56 is eccentric withrespect to the axis of the spindle 32 the disk 6% is eccentric theretoand will move in a circle above the surface of the lap rather than asingle point when the spindle is rotated; hence making use of aconsiderable area of the grinding surface of the lap and reducing thewear thereof;

, In order to clamp the stone securely so that it will not rotate aboutits vertical axis, that is, the axis which passes through the culet cand is normal to' the table T during the grinding operation, the leg l4must be drawn toward the leg 55 so as to hold the work under suificientpressure, as frictionally to engage its table T with the surface ill ofthe disk 68, and the shoulders 88 and H of the head 8 and the disk 68,respectively, with the legs i4 and 56 to lock them by friction againstany rotational movement. The head lit and disk 58 may for conveniencebereferred to as adapters. To this end an aperture 94 is provided in themid-portion of the leg 56 in which there is rotatably placed a spindle95 (Figs. 8 and 19) having a threaded end portion 98 which passesthrough a threaded aperture I535 formed in the leg M so that by rotationof thespindleiitthe leg it may be moved to or from the leg 56. Asillustrated, the spindle 96 is fixed so that'it does. not movewith'respect to the leg 56 by a locking ring 62 seated in a groove Mi lcut into the peripheral surface of the spindle and a groove 55 cut intothe inner surface of the aperture at. A knurled knob m8 at the outer endof the spindle provides for ease of rotation of the spindle.

Theuse of'the clamping disk 68 is advantageous in that its flat surfacemay easily be kept clean, and will accommodate the table of any sizestone without damage thereto by burning, scratching-0r otherwisedamaging the same. It has the further advantage that since it does notpositively grip the crown of the diamond when the stone is turned aboutits vertical axis by rotation of the member 34, the surface of the tablewill be unconstrained and will turn freely on the surface of the disk.Still another important advantage is that since the crown and table ofthe diamond arenot fixed either as to rotational movement or movement atright angles to its vertical axis whenthe clamping surface ishorizontal, that is, normal to the spindle 32 instead of inclinedthereto. The leg 58 is fixed between the Walls 52 in a verticalposition, that is, parallel to the axis of the spindle 32. The leg 'i l,the means for moving it to and from the leg 5%, and the work-engagingmembers correspond exactly to the construction described above with theexception that they in position and render the parts fixed.

worm s9 is then rotated to bring the dop vcrmembers .64 and Starebrought together, a litthereto.

will now be located in planes parallel and normal to the surface of thelap rather than inclined The spindle 82 in this case is parallel to thesurface of the lap and coincides with the vertical axis of the stone.The spindle 5% of the disk 52 is also parallel to the surface of the lapbut is not coincident with the vertical axis of the work beingspacedupwardly therefrom.

As a result the surface or table T of the stone is not concentric withthe axis of rotation of the disk 58 but is eccentric with respectthereto, that is, engages it in an ofi-center relationship.

In whichever form the apparatus takes, that is, whether the work is heldwith its vertical axis inclined to the surface of the lap or parallel tothe surface of the lap, it is apparent anysize stone may be mounted inthe dop, that the stone may rigidly be held at one end but free toalign'itself at the other end during the grinding operation, chatteringis eliminated, that the flat surface of the disc will eliminatescratching, that the work may be indexed to turn it about its verticalaxis from one position to the next position for grinding the successivefacet very readily and easily without touching the Work with the fingersand accurately so as to insure the correct location of the successivefacets, and that the work may be positioned by proper rotation of thedop as a whole around the vertical axis of the spindle 32 so that thegrinding will be performed ina direction which is substantially parallelto the grain of the stone at its point of contact with the lap. Thefreedom of vertical movement of the spindle 3'2 permits the stone torest on the surface of the lap solely by gravity. A dop provided withthe foregoing adjustments greatly facilitates and improves the accuracyof grinding, particularly with small stones which are difiicult tohandle with the fingers and which, if attached by cement to the dop,require considerable manipulation and a chance of error in forming theminute facets at the proper spacings and angles with respect to eachother.

In operation the stone is mounted with its table '1 in engagement withthe surface it of the 8d and with its pavilion P seated in the recess953 of the head 86, and then the leg is is drawn toward the leg 56 byrotation of the knurled knob l so as firmly to clamp the stone Thetically downward toward the surface of the lap 52 to engage the girdleportion G of the stone with the surface. "The play afforded by the sliding frictional engagement of the table T with the fiat surface'of thedisk 68 allows the. stone to align itself with the parts without damagethereto. The play afforded by the splined connection between the spindleand the sleeve perunits the stone to rest on the lap solely by thegravitational pull on the dop. Since the lower ends of the legs 56 andit are tapered, the girdle portion of the work will project downwardlyfrom their lower ends and be exposed for grinding to a maximum extentwithout being obscured or hidden by portions of the dop, and henceexamining and checking of the grinding operation will be greatlyfacilitated. After the stone has been fixed in position, the dop isturned about the vertical axis of the spindle 32 to bring the grainthereof substantially parallel to the direction of rotation of thegrinding surface at its point of contact therewith, the lay of the grainhaving been determined prior to mounting it in position. The motor isthen started so as to rotate the lap and hence to grind the facet, and,as soon as a given facet is completely ground, the stone may be indexedby rotating the knob I93 just sufficiently to relieve the frictionalengagement of the head 84 and the disk 68, whereupon by rotation of theknob 96 fastened to the spindle 82 the stone itself may be rotated aboutits vertical axis to bring the succeeding portion of the girdle into aposition to be ground without completely releasing the stone. By successively indexing the stone about its vertical axis, facets may beground throughout the peripheral area of the girdle accurately andrapidly.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A dop for holding a diamond in juxtaposition to the grinding surfaceof a rotating skeif comprising a body portion secured to one end of adop positioning spindle, and a diamond holding assembly mounted on saidbody portion, said assembly including a pair of relatively movable workholding jaws provided with work engaging elements, one of said jawsbeing fixed to the body portion, a pair of spaced parallel guides fixedat one end to the fixed jaw so as to be substantially perpendicularthereto, said other jaw having spaced openings therein to receive thespaced parallel guides to permit the movable jaw to slide freely to andfrom the fixed jaw, said work engaging elements being mounted on thejaws close to their free ends for rotation about eccentrically arrangedparallel axes parallel to the guides, one of said elements havingnon-rotatable engagement with the pavilion of the diamond the axis ofsaid one element being concentric with the pavilion engaging portionthereof and the other having a continuous fiat surface for engagementwith the table of the diamond, the center of said surface beingeccentric to the center of rotation of said one element, and a studjournaled in one of the jaws and having threaded ing a channel in itslower end, said channel being open at the bottom and being defined byspaced parallel side walls and an upper wall which is inclined to theaxis of the spindle, and

a diamond holding assembly mounted on said body, said assembly includinga pair of relatively movable work holding jaws provided with workengaging elements, one of said jaws being fixed at its upper end to thebody portion within the channel so as to be substantially normal to theinclined wall, a pair of spaced parallel guides fixed at one end to thefixed jaw so as to be substantially parallel to said inclined upperwall, said other jaw having spaced openings therein to receive thespaced parallel guides for sliding movement between the parallel wallsto and from the fixed jaw, and in parallel relation thereto, said jawshaving lower tapering ends and said work engaging elements being mountedat the tapering ends of the jaws for rotation about spaced parallel axesparallel to the inclined wall, one of said elements having non-rotatableengagement with the pavilion of the diamond, and the other having acontinuous flat surface for engagement with the table of the diamond,the center of rotation of said continuous fiat surface being eccentricto the center of rotation of said one element and the lowermostperipheral por-- tion of said continuous fiat surface being tangent tothe lowermost extremity of the jaw on which it is mounted and a studjournaled in one of the jaws and having threaded engagement with athreaded opening in the other jaw, said stud being rotatable to move thejaws to and from each other to clamp work between the work holdingelements and to immobilize the elements from rotation about their axes.

CHARLES A. HANS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 753,992 Marcher Mar. 8, 1904802,368 Coleman Oct; 24, 1905 969,871 Hornig Sept. 13, 1910 1,094,913Loesser Apr. 28, 1914 1,373,835 Ryon Apr. 5, 1921 1,646,375 AugensteinOct. 18, 1927 1,838,423 Loesser et al Dec. 29, 1931 2,383,619 RosnerAug. 28, 1945 2,435,971 Ludel Feb, 17, 1948

